Israel Patent Application No. 124,949 teaches a panel which comprises a plurality of rotatable members having an opaque surface, which members, when rotated, are adapted, in at least one angular position, to substantially block the passage of light through the panel, and, in a plurality of other, selectable angular positions, to provide a plurality of differing radiation transmissivities.
While the above-mentioned panel does indeed provide a steplessly adjustable light transmissivity, it has certain disadvantages, inasmuch as the rotatable light-blocking members are accommodated in an array of tubular cells of relatively large size and wall thickness, that add to the costs of these panels.